The present invention relates to a method and apparatus for making two envelopes at once. The device further includes improved methods for dealing with the associated problems with such a machine.
At one time all envelopes were made by hand, by cutting envelopes to size and gluing them together. The advent of mechanization of many other processes also brought about the mechanization of the envelope making process. It is almost unheard of to see a handfolded envelope these days. Most envelopes are made in mass production, on an envelope making machine, which performs all of the envelope functions including paper cutting, folding and gluing. This has made it possible to make envelopes at a relatively high speed, although higher speed is always desireable.
At the present time, state of the art envelope-making machines have a top speed of about 1,000 envelopes per minute. These envelope makers make one envelope at a time, and the end product can be of only one type. In order to make a different type envelope, the machine must be turned off, and reconfigured in some way.
It is an object of the present invention to at least double this possible speed available from a current envelope maker. It is also an object of the present invention to provide a machine which can simultaneously make more than one envelope at a time.
One of the big problems in making envelopes is the turn-around time for an order. The turn-around time for an order may be exacerbated if machines must be frequently taken down in order to reconfigure the machine. The necessity to frequently reconfigure these machines greatly decreases their efficiency.
Therefore, it is an object of this invention to make a machine which does not need to be configured as frequently.
Another problem of automated enveloped machines is the problem of tension on the "web". The envelopes are cut from a continuous roll of paper which is known in the art as a web. The tension on the web must be evenly maintained, or else wrinkles will form which could jam the machine, or at best form a low quality final product. The problems of tension on the web become exacerbated as the web gets wider. It is an object of the present invention to provide an improved technique of maintaining the tension on the web, even when the web is very wide.
Finally, another operation which is very time consuming is when the envelope machine runs out of paper. At this time, it becomes necessary to change the envelope machine roll. It is an object of the present invention to somewhat ameliorate these problems.
Various techniques have been used in the prior art to attempt to deal with these and other problems in envelope making machines. One such technique is U.S. Pat. No. 4,531,993 to Bradley. The disclosure of this patent is hereby incorporated by reference to the degree deemed necessary. Bradley shows, in FIGS. 1-11, the steps to folding a cut sheet of paper into an envelope. The Bradley envelope is a double folded type envelope, but shows the basic features of envelope folding. However, the problem with Bradley is the same as that of the prior art. Specifically, the Bradley technique could only accommodate one envelope at a time, and therefore would have to be reconfigured for each new kind of envelope. Moreover, this device is subject to the speed limitations of the prior art.
U.S. Pat. No. 3,565,728 defines a method and apparatus for forming a continuous assembly of articles, and apparently could be used for assembling devices like envelopes. However, there is no provision in Alton for forming more than one envelope at a time, nor of the structure of the present invention for maintaining a uniform tension on the web.
Finally, U.S. Pat. No. 1,503,155 to Haas shows an envelope making machine, but again, this has all the drawbacks of the prior art.